6 February 2014
Creating a
“legged” robot is one thing. Making it
run instead of walk is another. But,
then, there’s yet another challenge. Can
you make it run fast?
Developed
for DARPA by Boston Dynamics, the robo-cheetah’s claim to fame is its
speed. Modeled after the real-life
cheetah, this robot boasts a “cat-like spine,” which “flexes and extends” with
the robot’s galloping stride. And it gallops -- “constantly tipping forward,
falling, and regaining equilibrium with every step.” After the development of the first prototype,
in 2011, it was showcased running at speeds of up to 18 mph by March of 2012. By September, it clocked 28.3 mph – faster
than the fastest human runner in a hundred-yard dash.
Of course,
with all the excitement, Robo-Cheetah still had a couple issues that needed to
be ironed-out before it could go bounding across a battlefield. It was running at high speeds, but it was
only running on a treadmill. Still, it
was about ready to jump off the treadmill and, at least, onto flat ground.
Robo-Cheetah's biggest
issue was that it was still “tethered” by a power cord. In other words, it had to be plugged into a
wall socket to get the juice it needed to move. There’s no portable power pack for this ‘bot
that can store enough power to let it run free.
Portable power supplies are a big issue in robotics and one of the
biggest challenges to maximum performance.
There’s a tradeoff. You need enough power to allow the ‘bot to operate for long stretches of time. You, also, need a power pack light-weight enough for the ‘bot to carry. But, when you make the power pack light enough, there’s not enough power to run the ‘bot. And, when you make a power pack with enough power, the pack (and ‘bot) become so heavy that, now, . . . the 'bot's short on power -- again. It's like running in a circle.
There’s a tradeoff. You need enough power to allow the ‘bot to operate for long stretches of time. You, also, need a power pack light-weight enough for the ‘bot to carry. But, when you make the power pack light enough, there’s not enough power to run the ‘bot. And, when you make a power pack with enough power, the pack (and ‘bot) become so heavy that, now, . . . the 'bot's short on power -- again. It's like running in a circle.
But, soon,
there were more than technical challenges – there were challengers. The first competitor was MIT. The Biomimetic Robotics Lab at MIT, also under
the sponsorship of DARPA, was, and is, working on its own version of the robo-cheetah. MIT is trying to recreate the running
movement of the real cheetah. They’re more
public with their work. The MIT website
shows their version of Robo-Cheetah.
Their robot can’t run as fast as the Boston Dynamics model, but MIT’s model
boasts a “highly efficient leg motor,
imitation tendons,
and a responsive tail.” With these improvements MIT’s Robo-Cheetah
has a rhythm and movement completely different from other four-legged ‘bots.
MIT's
Robo-Cheetah, also, “will” run on a battery (but it, too, is still plugged into
a wall-socket). Unlike the other
Robo-Cheetah, MIT’s uses a surprisingly simple and more effective way of
regulating its leg motion – one without the usual sensors and complicated computer
feedback-loops that were, and are, still a common part of robotic technology.
But what’s
so important about imitating a real cheetah?
The robo-cheetah is one of a group of DARPA-funded projects applying the concepts of
biorobotics. To meet DARPA’s
requirements, drones must be built to perform more like . . . wildlife. The term “biomimetics” or “biomimicry” is
used to describe the development of technology designed to imitate and
replicate the activities of biological systems and organisms. But, why imitate nature? Well, “if you want drones that work in a
particular way, and the only known example of such performance is a biological
organism, you’ll either have to imitate the organism or forget the project altogether.”
The need
for walking (rather than rolling) robots is a prime example. The jeep took “a basic automobile and raised
the center of gravity, increased the size and scale of the automotive
suspension system and produced spectacular off-road performance for a machine
with wheels.” But the wheel, itself, was limited. Human beings,
horses, mules, and dogs can all travel over terrain that would be impossible for
any wheeled vehicle to handle.
How do you
design a ‘bot that travels over rough terrain like a mule? Well, you design it . . . like a mule. And Boston Dynamics' “Robo-Mule” (later,
renamed “BigDog”) was the first in a new line of bio-inspired “walking”
robots. But, again, why a cheetah? Is it just a cool sounding name or is it the sleek
look of the moving animal? Neither. There’s something special about cheetahs that
DARPA wants to capture in robotic performance.
Robo-Cheetah
is being designed to move, quite specifically, like a cheetah. Unlike Robo-Mule (“BigDog”), Robo-Cheetah is
meant to be ultra-speedy and agile, able to “chase and evade” like the actual animal. Designers are working on getting it to run at
cheetah speed, but their ultimate ambition goes much farther than that. They hope to design a ‘bot that can run faster
than any animal on earth -- as fast as 70 mph.
Robo-Cheetah
will have many military applications, including emergency and disaster
response. But DARPA has hinted at
performance that might improve on nature.
At least, humans might be able to do things with Robo-Cheetah you’d
never try with the real thing – including uses in “advanced agriculture and
vehicular travel.” Just think. Riding a Robo-Cheetah!
Of course,
the pressure rose with two Robo-Cheetahs in development: The speedy one by
Boston Dynamics and the graceful one by MIT. But, the race got even tighter when another competitor
came out of left field -- the Robo-Ostrich.
Ostrich? What’s an ostrich got to
offer in this race? An ostrich is a bird, and it
can’t even fly. Well, fly it can’t, but
maybe it doesn’t need to because the ostrich is the fastest land animal on
earth.
DARPA has funded the joint effort of
MIT and the Florida Institute of Human and Machine Cognition (IHMC) in a
project to develop a robot that walks and runs. But the end result of
this latest effort will be the first robotic biped in the DARPA arsenal -- a robotic ostrich.
Robo-Ostrich is designed not just to walk, but to run and
run fast. Although the first full prototype has yet to be designed, the
working computer simulation has legs and is hitting speeds of 27 mph.
Impressive, again, because this is about the speed of the fastest human runner in
a hundred yard dash.
Robo-Ostrich’s
designers are only hoping for a maximum speed of 50 miles an hour – faster than
the fastest ostrich -- clocked at 43 mph.
On the other hand, this is a bit slower than the 70 mph Boston Dynamics
is hoping for Robo-Cheetah. But there’s
“a whole ‘lot of hoping going on” here.
Robo-Cheetah isn’t off the treadmill, and Robo-Ostrich is a computer simulation. We’ll just wait and see.
What’s the
secret of Robo-Ostrich’s speed? Two
legs. What’s so special about a
two-legged robot? Not only is a
two-legged robot lighter than a robot with twice the number of legs, but its movements
are more flexible allowing it to, among other things, “get through narrower
spaces” and maneuver more easily around obstacles. With such a flexible
build, this robot, like other “be-footed” robots, is designed to negotiate
rough terrain that would defy a wheeled-vehicle like a jeep. Even on the
most irregular surfaces, the finished ‘bot is expected to run (or walk) at a
speed of 10 mph, more than twice as fast as a walking human being.
Well, with
MIT pushing hard to the goal with both their robots, Robo-Cheetah and Robo-Ostrich,
Boston Dynamics had to do something.
They announced their plan to take the lead in the race, by unleashing
Robo-Cheetah from its treadmill. They
promised their Robo-Cheetah, unteathered,
would hit the road in 2013. And it did,
but with a twist.
In 2013,
the cordless “Wildcat” was shown galloping and running (and even running backward) on flat
terrain. But, wait, what happened to
Robo-Cheetah? Why the Wildcat? Why Robo-Cheetah's little sister?
To speed up
development, Robo-Cheetah was . . . modified. To get rid of its power cord and, then, to get it off the treadmill
and onto the ground, Robo-Cheetah had to lose some of its bulk and weight. It, also, lost its electric motor and gained
an internal combustion (gasoline powered) engine. Even with these reductions, it lost
some of its treadmill speed -- slowing from 28 to about 16 mph.
The Wildcat may be slower than the fastest human in a hundred yard dash but, if its chasing you, you’d better get to safety within that hundred yards. Why? Because the Wildcat will still be going strong and fast long after you, I, or any human runner, would have worn out and fallen to the ground. The Wildcat still only performs on flat terrain, but the plan is to have it walking on the same rough ground that its distant cousin the Robo-Mule/BigDog handles with ease.
The Wildcat may be slower than the fastest human in a hundred yard dash but, if its chasing you, you’d better get to safety within that hundred yards. Why? Because the Wildcat will still be going strong and fast long after you, I, or any human runner, would have worn out and fallen to the ground. The Wildcat still only performs on flat terrain, but the plan is to have it walking on the same rough ground that its distant cousin the Robo-Mule/BigDog handles with ease.
The Wildcat
Thursday 6 February 2014
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